A high-efficiency single-phase inverter for transformerless photovoltaic grid-connection

Leakage current is a critical issue in transformerless PV systems, which creates safety and EMI problems. The traditional full-bridge inverter using unipolar sinusoidal pulse-width modulation suffers from high-frequency leakage currents. To solve the problem, this paper proposes a singlephase inverter for transformerless PV generation systems. The proposed topology significantly reduces the leakage current by AC-decoupling and common-mode voltage clamping. Additionally, high efficiency is achieved because of the low conducting losses compared with conventional transformerless topologies. Also, the proposed topology is symmetrical and power device losses are reasonably balanced, for good thermal design and prolonged inverter life time. The common-mode performance of the proposed topology is verified by simulation and experimentally with a 2kW system.